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A multi-tracer test was conducted in sub-vertical fractures in a low-permeable Eocene chalk aquitard in the northern Negev desert, Israel. The test was performed in two inclined wells, located 10 m apart, which are directed normal to the strike of the major fracture system on site. A forced gradient with steady water level was maintained. Tracers' solution containing uranine, LiCl and 2,4,6-tribromophenol (TBP) were injected into one well and collected in the pumped well. Breakthrough curves (BTCs) of these tracers were modeled and the fracture system parameters were estimated. Two different models of parallel plates were used for interpretation of experimental data. The first one is a single-fissure dispersion model (SFDM) that describes advective-dispersive transport in the fractures coupled with diffusive transport into adjacent rock matrix. This model consists of three fitting parameters. The second one is a parallel plate boundary layer model (PPBLM), which is similar in general to the SFDM, however, in addition, it takes into account the existence of the intermediate layer between fracture wall and the porous matrix. The latter model has one additional fitting parameter, which accounts the rate-limited mass transfer through the mentioned layer. Parameters of both models were found separately for each tracer by fitting theoretical BTCs to the experimental data. Similar values of fracture aperture, dispersivity and flow velocity were obtained for both models. However, the molecular diffusion coefficients of the above mentioned tracers calculated using SDFM were about seven times lower than those found in the literature. Simulations of multi-tracers experiments indicate that only 6-7% of the total number of fractures are interconnected.